Advertisements
Advertisements
Question
Calculate the maximum kinetic energy and maximum velocity of the photoelectrons emitted when the stopping potential is 81 V for the photoelectric emission experiment.
Advertisements
Solution
V0 = 81 V
e = 1.6 × 10−19 C
m = 9.1 × 10−31 kg
Maximum kinetic energy of electron,
Kmax = `"eV"_0`
= 1.6 × 10−19 × 81
= 129.6 × 10−19
= 1.29 × 10−17
Kmax = 1.3 × 10−17 J
Maximum velocity of photoelectron,
vmax = `sqrt((2"eV"_0)/"m")`
= `sqrt((2 xx 1.6 xx 10^-19 xx 81)/(9.1 xx 10^-31))`
= `sqrt((259.2 xx 10^-19)/(9.1 xx 10^-31))`
= `sqrt(28.48 xx 10^12)`
vmax = 5.3 × 106 ms−1
APPEARS IN
RELATED QUESTIONS
A photoelectric surface is illuminated successively by monochromatic light of wavelength λ and `λ/2`. If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the material is
Two radiations with photon energies 0.9 eV and 3.3 eV respectively are falling on a metallic surface successively. If the work function of the metal is 0.6 eV, then the ratio of maximum speeds of emitted electrons in the two cases will be
If the mean wavelength of light from sun is taken as 550 nm and its mean power as 3.8 × 1026 W, then the average number of photons received by the human eye per second from sunlight is of the order of
The work functions for metals A, B and C are 1.92 eV, 2.0 eV and 5.0 eV respectively. The metal/metals which will emit photoelectrons for a radiation of wavelength 4100Å is/are
How will you define threshold frequency?
What is a surface barrier?
How many photons of frequency 1014 Hz will make up 19.86 J of energy?
When a light of frequency 9 × 1014 Hz is incident on a metal surface, photoelectrons are emitted with a maximum speed of 8 × 105 ms−1. Determine the threshold frequency of the surface.
At the given point of time, the earth receives energy from the sun at 4 cal cm–2 min–1. Determine the number of photons received on the surface of the Earth per cm2 per minute. (Given: Mean wavelength of sunlight = 5500 Å)
UV light of wavelength 1800 Å is incident on a lithium surface whose threshold wavelength is 4965 Å. Determine the maximum energy of the electron emitted.
